This application is based on an application No. 282751 filed in Japan on Sep. 18, 2000, the content of which is incorporated herein by reference.
This invention relates to an apparatus provided with spring-loaded contacts that can reliably make electrical connection with terminals of electrical equipment attached in a detachable fashion.
There are various combinations of apparatus with electrical equipment attached in a detachable fashion. For example, a DVD player may be attached to in a detachable fashion to a power supply housing batteries to supply power to the DVD player. Here, the power supply is the apparatus and the DVD player is the electrical equipment. Apparatus and electrical equipment, which attach in a detachable fashion, make electrical connection via spring-loaded contacts as described, for example, in Japanese Patent Application HEI-7-19949 (1995). Spring-loaded contacts are provided with flexible arm segments and these flexible arm segments resiliently press connection segments against electrical equipment terminals to prevent contact failure. However, even with this configuration, contact failure problems cannot be solved in an ideal fashion. In particular, the probability of contact failure increases as time of use increases.
The probability of contact failure can be significantly reduced by making contact to a single terminal with a plurality of spring-loaded contacts For example, if the probability of one contact failing after a given time of use is {fraction (1/100)}, the probability of contact failure for two redundant contacts is significantly reduced at {fraction (1/100)}xc3x97{fraction (1/100)}={fraction (1/10000)}. Further, in the case where a contact supplies high current, a plurality of contacts can divide up that current for supply. This has the characteristic that effective contact resistance and the voltage drop across the contacts can be reduced.
FIG. 1 shows a plurality of spring-loaded contacts 104 connected to terminals. The spring-loaded contacts 104 of this figure are provided with a first spring-loaded contact 104A and a second spring-loaded contact 104B to connect with two terminals of the electrical equipment. The first and second spring-loaded contacts 104A, 104B are provided with connection segments 104a to connect with terminals, attachment segments 104b to attach to the board or substrate, and flexible arm segments 104c between the attachment segments 104b and the connection segments 104a. The spring-loaded contacts 104 of FIG. 1 are oriented in opposition with connection segments 104a of the first and second spring-loaded contacts 104A, 104B in close proximity. Specifically, the flexible arm segments 104c of the first and second spring-loaded contacts 104A, 104B are disposed on both sides of the connection segments 104a. 
When the connection segments 104a of the first and second spring-loaded contacts 104A, 104B are pushed down by electrical equipment terminals, they move in the directions indicated by the arrows A and B of FIG. 1. Specifically, the connection segments 104a of the first and second spring-loaded contacts 104A, 104B incline and move towards each other as they are pushed down. Both connection segments 104a do not move in parallel in the same direction as they are pushed down. Connection segments which do not move in the same direction will have excessive force applied to one side or the other when electrical equipment is attached, and both connection segments cannot connect to terminals in an ideal fashion. For example, when electrical equipment is attached in the direction indicated by the arrows a or b of FIG. 1, the first spring-loaded contact 104A bends smoothly, but the second spring-loaded contact 104B cannot bend smoothly. This is because the second spring-loaded contact 104B bends in the direction indicated by arrow B, but does not move in the direction of electrical equipment attachment. Therefore, this system has the drawback that the second spring-loaded contact 104B can be damaged and contact failure can occur easily.
This problem can be solved by orienting the first and second spring-loaded contacts in the same direction. For example, as shown in FIG. 2, the connection segments 204a of the first spring-loaded contact 204A and the second spring-loaded contact 204B can be disposed in the same manner at the right ends of the spring-loaded contacts. However, spring-loaded contacts 204 arranged in this fashion result in shorter flexible arm segments 204c for the second spring-loaded contact 204B and thus a shorter bending stroke. This problem can be solved by widening the distance between the connection segments 204a of the first and second spring-loaded contacts 204A, 204B. However, since the distance between the connection segments of the first and second spring-loaded contacts is determined by the distance between electrical equipment terminals, that distance cannot be widened indefinitely. This is because the terminals of almost all electrical equipment are disposed in close proximity to one another. Therefore, two connection segments which connect to closely spaced terminals must be disposed close to one another. Consequently, spring-loaded contacts configured as shown in FIG. 2 have the drawback that the spring-loaded contact with the short bending stroke cannot press smoothly against a terminal for electrical connection and can be easily damaged.
The present invention was developed to solve these problems. Thus it is a primary object of the present invention to provide an apparatus with spring-loaded contacts which can make stable connection to closely spaced terminals and radically reduce contact failure over long time periods. The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.
The apparatus with spring-loaded contacts of the present invention is provided with spring-loaded contacts to resiliently press against, and make electrical connection to terminals of electrical equipment attached in a detachable fashion. These spring-loaded contacts are provided with a first spring-loaded contact and a second spring-loaded contact disposed close to one another. The first and second spring-loaded contacts are provided with connection segments which connect with electrical equipment terminals, attachment segments which attach to the board or substrate, and flexible arm segments between the attachment segments and the connection segments. The flexible arm segments can bend to resiliently press the connection segments against electrical equipment terminals. The first spring-loaded contact and the second spring-loaded contact are each provided with a pair of connection segments disposed in close proximity. The pair of flexible arm segments connected to the pair of connection segments on the first spring-loaded contact has a widened region where the flexible arm segments extend towards the connection segments of the second spring-loaded contact. Part of the second spring-loaded contact is disposed within the widened region of the first spring-loaded contact.
The first and second spring-loaded contacts can be made the same shape. Further, the flexible arm segments of the first and second spring-loaded contacts can be oriented to extend in the same direction.
A spring-loaded contact with two connection segments can be formed from a single strand of flexible wire material or from two strands of flexible wire material. The spring-loaded contacts can be mounted in holders to retain them in fixed positions.
An apparatus with spring-loaded contacts configured as described above is characterized by the capability to make stable connection to closely spaced terminals and to radically reduce contact failure over long time periods. This is because the first and second spring-loaded contacts, which are provided with connection segments that connect with terminals, attachment segments that attach to the board or substrate, and flexible arm segments that bend, are disposed close to one another. This is also because the first and second spring-loaded contacts are each provided with a closely spaced pair of connection segments, and the pair of flexible arm segments connected to the pair of connection segments on the first spring-loaded contact has a widened region where the flexible arm segments extend towards the connection segments of the second spring-loaded contact. This configuration of apparatus with spring-loaded contacts has one part of the second spring-loaded contact disposed within the widened region of the first spring-loaded contact. Namely, the first and second spring-loaded contacts can be disposed with one part of the spring-loaded contacts overlapping. Consequently, the first and second spring-loaded contacts can be disposed close to one another and can make stable connection to closely spaced terminals. Further, by disposing the first and second spring-loaded contacts with the same orientation, the second spring-loaded contact can bend smoothly with an optimal stroke. Therefore, spring-loaded contacts can press against, and make electrical connection to terminals without application of excessive force, and spring-loaded contact damage can be prevented to radically reduce contact failure.